plexi case tips needed

Hi everyone I'm now ready to case my mp3 player and I'm going to use a plexi case.
Now I've read as much as I can find on this issue, but I was wondering if anyone has some "does and don'ts" from their own experience. BTW mine is going to be a Home MP3 player does this make any difference? in the build.
After this I think I'm ready to put one in my BMW E30 has anyone got any pics of an installation in a E30.